Method of conveying metallic sheets



' March 17, 1942. F. EBERHART METHOD OE CONVEYING METALLIC SHEETS Filed Oct. 20, 1939 HW M M W wN m NW. N? w m a NT u u u o ing, discloses a along a plane indicated by the line 1, parts being broken v shown in section;

Patented Mar. 17, 1942 2,276,472 DIETHOD OF CONVEYING METALLIC SHEETS Felix Eben-hart, Arlington, American Can Company, corporation of New Jersey N. J., assignor to New York, N. Y a

Application Dctober 20, 1939, Serial No. 300,478

2 Claims,

The present invention relates to a method of conveying metallic sheets and the like and has particular reference to magnetically attracting metal sheets into close contact with a non-magnetic conveyor while predetermined location and spaced relation on the conveyor to prevent shifting.

In certain respects the'invention is related to i the improvements disclosed and claimed in my copending applications Serial No. 300,476 and Serial No. 300,477, filed of even date herewith.

The primary object of the instant invention is the provision of a method of conveying flexible metal sheets wherein the sheets are carried on a non-magnetic conveyor in predetermined spaced relation and are drawn into intimate contact with the conveyor by means ing force which progressively increases in intensity as the sheets enter upon or leave the conveyor so that there will not be any shifting of the sheets from their predetermined positions and consequent scratching of the surface thereof will be prevented.

Numerous other objects and advantages of the invention will be apparent asit is better understood from the following description, which, taken in connection with the accompanying drawpreferred embodiment thereof.

Referring to the drawing:

Figure 1 is a side elevation of an apparatus for carrying out the steps of the instant method invention, with parts broken away;

preserving the sheets in a of a magnetic hold- Fig. 2 is a top plan view taken substantially away and other parts being 2-2 in Fig.'

Fig. 3 is an enlarged longitudinal sectional detail of devices located apparatus. with parts broken away; and

Fig. 4 is an enlarged transverse sectional detail taken substantially along the line 4-41 in Fig. 2.

As a preferred embodiment of the instant invention the drawing discloses ing metallic sheets of tinplate which by way of example are coated on one side with a dried coating which may be easily scratched and are coated on the opposite side with a lithographing or print which as the sheets are received is still wet, and .it is this newly applied coating which is adapted to be dried or baked in the apparatus disclosed. The dimculty usually encountered in handling such sheets is absent when treating them in accordance with the steps of the instant method.

at the entrance end of the .ceived in the freshly printed or rectly from the lithographing press by way of an the entrance end of the drying In such a method the sheets are carefully fed onto a continuously moving non-magnetic surface, preferably a smooth flat conveyor on which the sheets may be carried along a predetere mined path of travel past operating stations at which subsequent operations may be performed on the sheets. In order to avoid scratching the sheets on either the fresh or the dried coating, they are held stationary on the moving surface so that they will not shift relative to the surface.

As a step in the instantmethod this holding action is obtained by moving the surface adjacent and through a magnetic field of gradually increasing intensity so that the sheets will be first gradually attracted to the surface in a manner which will prevent their jumping ahead or slid which they will not shift relative to the surface but will be held to it while traveling therewith. The drawing shows one selected form of apparatus for carrying out these method steps and this form preferably comprisesca drying oven A (Fig. l) for baking lithographed tinplate sheets although the invention .is equally well adapted to other kinds of apparatus. The lithographed sheets indicated by the letter B are preferably rewet condition diendless feed-in belt H which is disposed adjacent oven A and which is actuated in any suitable manner in time with the oven parts. Adjacent the drying oven the feed-in belt takes over a pulley I2 which is mounted on a, cross-shaft it carried in bearings H of a pair of spaced brackets frames l6 which constitute the main frame of the drying oven.

The wet sheets B fed into the drying oven A are received on a plurality of narrow spaced and parallel endless belt conveyors 2| which extend a method of treatout the use of a transfer device and without damaging the sheets by scratching them.

At the entrance end of conveyors 2| take over a wide pulley 22 which is disposed bet-ween the side frames l6.- The pulley is mounted on an idler cross-shaft 28 Jour- I5 secured to side the drying oven A the naled in bearings 24 formed in the brackets l5. At the opposite or discharge end of the oven the conveyors take over a wide pulley 26 which is mounted on a drivingross-shaft 21 joumaled in bearings 28 formed in brackets 23 secured to the side frames IS. A driving gear 3| mounted on a projecting end of the drive shaft is provided for rotating the shaft and thereby actuating the conveyors, in time with the feeding belt I I. This gear may be rotated from any suitable source of power such as an electric motor or other prime mover.

The conveyors 2| are maintained in a taut condition by a tightening pulley 33 which engages against their lower runs. ed on a cross-shaft 34 the ends of which are carried in spring held arms 35 which swing on a cross-shaft .36 carried in bearings 31 secured to the oven side frames IS.

The upper runs of the conveyors are supported against sagging by a plurality of rollers 40 (see also Figs. 3 and 4) over which the conveyors travel. These rollers are formed with trunnions 38 which operate in spaced notches 39 provided in horizontally disposed channel beams 4| which extend between the conveyor pulleys 22, 26.

This pulley is mount- There are preferably three of these channel beams, one arranged below each conveyor 2| and they are supported on cross beams 42 which are secured to the oven side frames IS. The rollers extend across the width of the channel beams and are arranged in a staggered arrangement over the entire area between the conveyor pulleys so that the conveyors will be amply sup ported. i v The step of holding the wet sheets, received on the conveyor, in a stationary position relative to the conveyor is effected by a magnetic field hereinbefore mentioned which is located directly under the conveyors in spaced relationthereto and which extends the full length of the oven between the conveyor pulleys. This magnetic field is created by a plurality 0 long and short permanent magnets 45, 48 of U-shaped cross section and which are distributed in a staggered arrangement through the area over which the conveyors travel. These magnets are secured to the channel beams ll and are insulated therefrom by insulating blocks 41.

Thelong magnets 45 are disposed between the conveyor supporting rollers 31 and extend up toward the conveyors and terminate just below the bottom surfaces thereof so that they do not touch the conveyors. This constitutes'a holding zone of substantially constant or preferably maximum magnetic intensity or pull which is exerted at right angles or in a direction normal to a flat surface of the treated sheets. The short magnets are positioned adjacent the conveyor pulleys 22, 26 at the feed-in end constituting an entrance zone end and at the discharge end of the oven where they constitute an exit zone. These short magnets are located relatively close to each other and are disposed on an incline to the conveyors, as best shown in Fig, 3. For this purpose the ends of the channel beams are bent or inclined downwardly at an angle as indicated at 49 (Fig. 3) so that the magnets will be held in a proper position.

With this arrangement of the short magnets 46 the distance between the magnets and the conveyors vary in accordance with their location on the inclined portion of the chann :l beams. Hence the intensity of the magnetic pull, of the lowermost inclined magnet, on a sheet traveling overhead on the conveyors will be less than the next higher magnet on the incline and so as each magnet on the incline is closer to the conveyors its magnetic pull relative to the conveyor is greater. In other words beginning with the lowermost magnet on the incline the intensity of the magnetic field increases relative to the conveyor as a sheet thereon passes along a horizontal path of travel through the entrance zone toward the highest magnet on the incline. This intensity of the magnetic pull is indicated in Fig. 3 by short arrows.

Hence as the conveyors carry the wet sheets over the magnetic field, the sheets are gradually brought under the influence of the pull of the magnets on the incline 49 and are thus gradually drawn down tight against the conveyors without jumping ahead or sliding on the conveyors. This prevents scratching of the under coat on the sheets. By the time the sheets reach the long magnets 45 in the holding zone the full force of the magnets is applied to them so that they will be held against shifting as they travel along with the conveyors by means of a magnetic force or pull which is substantially constant and preferably of maximum intensity.

While traveling with the conveyors the sheets are operated upon. In the presentexample they are shown as being subjected to a heat treatment which drys or bakes the lithographing on the sheets.- For this purpose the oven A is formed with an enclosing hood 53 which is secured to the side frames Hi. This hood extends over the top of the conveyors throughout the entire length of the oven and also extends down adjacent the sides of the frames 16.

At the top of the hood 53 there is provided an outlet pipe 54 to permit escape of excess heat and to draw off volatile fumes of the lithographing solvents. Inside the hood a plurality of heating devices 55 preferably gas burners, are dis-,

source of gas supply.

The sheets after traveling the length of the oven A are thoroughly dry and are ready to be discharged from the oven. The conveyors therefore carry the sheets out of the region of the magnetic field of the holding zone, through the exit zone and thereby release the magnetic pull on them so that they may be readily transferred from the conveyors. This releasing step operable in the exit zone is effected gradually in the same manner but in the reverse order to that of the sheets when they were first attracted to the conveyors.

For this purpose there is provided adjacent the discharge end of the conveyors and effective in the exit zone another group of the short magnets 46 arranged on an inclined portion 58 of the channel beams 4|. It is these magnets and their increasingly lowered position relative to the conveyors that effect the gradual release of the sheets from the conveyors by reason of the progressively decreasing magnetic pull thereon, and thereby further prevent scratching of the sheets during this release.

The released sheets are discharged from the oven A- by way of an endless discharge belt 6| which is actuated in any suitable manner in time with the oven conveyors. This belt takes over a pulley 82 which is mounted on a cross shaft 53 carried in bearings 64 formed in the conveyor pulley brackets 29. The upper run of the discharge belt is disposed in the same plane as the upper runs of the conveyors 2|. Hence as the dried sheets leave the conveyors they readily run ofi onto the discharge belt and are thus carried to any suitable place of deposit.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will he apparent that various changes maybe made in the steps of the process described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificingall of its material advantages, the process hereinbefore describedbeing merely a preferred embodiment thereof.

I claim;

scratching of the treated surface of the sheet due to shifting of the same relative to the supporting medium is prevented during subjection of the sheet to the described magnetic pull of varying intensity in said magnetic field.

2. A method of handling and treating flexible metallic sheets having treated surfaces, which consists in supporting the sheets by means of their treated surfaces while moving the sheets in piocessional order in a predetermined path of travel through a magnetic field of varying intensity including an entrance zone, a holding zone 1. A method of handling flexible metallic sheets having treated surfaces, which consists in supporting-the sheets by means of their treated surfaces while moving the sheets in processional order in a predetermined path of travel through a magnetic field of varying intensity including an entrance zone, a holding zone and an exit zone, subjecting a said moving sheet in such field to a magnetic pull exerted in a direction normal to the plane of said sheet to draw and hold the same firmly and intimately against the V supporting medium, progressively increasing the intensity of said magnetic pull as the sheet moves through said entrance zone to prevent'jumping of the sheet relative to the supporting medium, I maintaining said magnetic pull substantially constant while the sheet is moving through said holding zone, and progressively decreasing the magnetic pull exerted on said sheet as the latter is moved through said exit zone. whereby and an exit zone, subjecting a said moving sheet in such field to a magnetic pull exerted in a direction normal to the plane of said sheet to draw latter is moved through said exit zone, whereby scratching of the treated surface of the sheet due to shifting of the same relative to the supporting medium is prevented during subjection of the sheet to the described magnetic pull of varying intensity in said magneticfield, and subjecting the outer exposed surface of said sheet to a treating operation while the supported sheet is moved through and subjected to the varying pull exerted by said magnetic field.

' FELIX EBERHART. 

